Plasma Exhaust Baffle Plate Rectifying Plate Uniformity
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Solution Overview
Problem
In plasma processing apparatuses, non-uniform pressure and flow velocity distributions across the substrate due to uneven exhaust gas distribution lead to critical dimension non-uniformity, making it challenging to maintain consistent processing conditions.
Innovation Solution
The apparatus incorporates a baffle plate with varying through hole sizes and a rectifying plate within the exhaust path to adjust the exhaust gas flow, ensuring a more uniform distribution by decreasing exhaust conductance closer to the exhaust device and increasing it farther away, thereby reducing pressure and flow velocity deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the exhaust device is provided at a position spaced away from the top of the central axis of the substrate, then the exhaust device can be disposed in the exhaust path, but the exhaust amount of the processing gas becomes non-uniform in the circumferential direction
Solution Approach 1:
The baffle plate is designed with through-holes having different opening areas at different radial positions. Specifically, through-holes closer to the exhaust device have smaller opening areas, while through-holes farther from the exhaust device have larger opening areas. This local variation in opening area compensates for the non-uniform exhaust distribution caused by the offset exhaust device position, achieving uniform exhaust amount across the substrate surface.
2Manufacturing precision
If the opening area of through holes in the baffle plate is decreased closer to the exhaust device and increased farther from the exhaust device, then the exhaust amount becomes uniform, but the device complexity increases
Solution Approach 1:
The opening areas of the through-holes in the baffle plate are varied according to their radial position relative to the exhaust device. By changing the opening area parameter spatially, the exhaust conductance is adjusted to compensate for position-dependent flow variations, achieving uniform exhaust distribution without requiring multiple baffle plates or complex adjustable mechanisms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively suppresses deviations in pressure and flow velocity across the substrate, enhancing the uniformity of processing conditions and reducing critical dimension non-uniformity, allowing for consistent processing under various conditions without the need for frequent baffle plate changes.
Implementation Method 1
decrease an opening area of a through hole closer to the exhaust device and increase an opening area of a through hole farther from the exhaust device. Accordingly, in the circumferential direction of the substrate, an exhaust conductance becomes lower at a position closer to the exhaust device, and becomes higher at a position farther from the exhaust device.
Implementation Method 2
a rectifying plate provided around the placing table to surround the placing table within the exhaust path at a position farther from the processing space than the baffle plate. The rectifying plate forms an opening within the exhaust path around the placing table to make a sectional area of a flow path within the exhaust path larger at a position farther from a position within the exhaust path connected to the exhaust device.
Data Source
AI summary
A plasma processing apparatus includes: a chamber; a placing table; an exhaust path provided around the placing table to surround the placing table, and configured to exhaust a gas within a processing space above the semiconductor wafer placed on the placing table; an exhaust device configured to exhaust the gas within the processing space through the exhaust path; a baffle plate having a plurality of through holes and provided between the processing space and the exhaust path to surround the placing table; and a rectifying plate provided around the placing table to surround the placing table within the exhaust path at a position farther from the processing space than the baffle plate, and forming an opening within the exhaust path to make a sectional area of a flow path within the exhaust path larger at a position farther from a position within the exhaust path connected to the exhaust device.